The present invention relates to an improved mechanism for driving a shaft of a station of a reproduction apparatus, such as a shaft of one or more development stations of an electrographic copier/duplicator or printer.
It is known to bolt a drive mechanism for a shaft of a development station to a mechanism plate near the rear of a reproduction apparatus, such as a copier/duplicator. Power is applied to the station from the back side of the mechanism plate through a gear or sprocket. A development station is located at the front side of the mechanism plate, and it is moved on guides into and out of engagement with the drive mechanism. As the development station is moved toward the drive mechanism from the front side of the plate a shaft of the station passes through an opening in the plate and enters a clutch of the drive mechanism. Guides mount the station in the apparatus so that the station moves in a direction substantially parallel to the axis of the shaft to engage the shaft with the drive mechanism and disengage the shaft from the drive mechanism.
Some reproduction apparatus have two or more development stations for applying toners of different colors to latent images to produce copies in one or more colors of an original document. When the apparatus has two development stations, one station typically has developer material comprising black toner particles and the other development station has development material comprising another color toner particles, such as red, green, blue, etc. Sometimes four development stations are provided with one station furnishing black toner particles to the latent image and the other stations furnishing cyan, magenta, and yellow toner particles to a latent image to provide full process color reproductions of the original document.
When more than one development station is provided in a reproduction apparatus, there may be times when only one of the stations is to be operated. For example, reproduction of a black original solely with black toner particles would require operation of only one development station. Thus, while the black station is operating any other station needs to be at idle or rest. Such can be easily accomplished by providing separate motor and drives for each development station. However, separate drives increases the cost of the apparatus and requires a significant amount of space in the reproduction apparatus. Also, when the reproduction apparatus has provision for two or more development stations, one station may be in place and operable at a time when another station has been removed from the apparatus. If a common drive for all development stations is used, then the drive for the removed station may be driven from a power source even when the station is not present in the machine. Thus there is a need for an improved drive mechanism for development stations of reproduction apparatus which are operable under each of three conditions of operation, i.e., when the station is loaded in the copier and the station is running, when two stations are loaded in the copier and one station is being operated while another is at rest or not running, and when the station is removed from the copier but the mechanism is driven as part of a drive for another development station in the copier.
Another problem with drive mechanisms for development stations of reproduction apparatus is a direct coupling between a power source and a driven shaft of the station can cause surges of torque to be applied directly to the shaft each time the power source is cycled on or off, either directly or through a clutch in the drive mechanism. Such a surge of torque can create maintenance and repair problems and, accordingly, it is desirable to provide a mechanism for controlling torque surges directly to the shaft of the development station.